If you stand outside on a clear autumn day, it becomes pretty apparent that Earth gets most of its heat from the Sun. Some heat comes from inside Earth — from the decay of radioactive elements. On balance, though, Earth gets far more energy from the Sun than it produces on its own.

That’s not the case with many of the other planets in the solar system, though. In fact, the largest planet of them all radiates about 70 percent more energy into space than it receives from the Sun.

Jupiter produces that energy because it’s big and heavy — it’s more than twice as massive as all the other planets and moons combined.

Because of that heft, its gravity is quite strong. That squeezes the planet tightly, heating its interior. The heat makes its way through the planet’s outer layers and radiates into space as infrared energy. In fact, if our eyes were tuned to the infrared instead of visible light, Jupiter would look even brighter than it does now.

And that’s saying something, because Jupiter is already the third-brightest object in the night sky — only the Moon and the planet Venus outshine it. And Jupiter and the Moon team up tonight. They rise in early evening, with brilliant Jupiter just to the right of the full Moon.

November’s full Moon, by the way, is known as the Wolf Moon or Hunger Moon — names that reflect the colder days ahead as the northern hemisphere receives less energy from Earth’s main source of warmth: the Sun.

Script by Damond Benningfield, Copyright 2011

Bookmark or share this page

For more skywatching tips, astronomy news, and much more, read StarDate magazine.

Keywords

Get Premium Audio

Listen to today's episode of StarDate on the web the same day it airs in high-quality streaming audio without any extra ads or announcements. Choose a $8 one-month pass, or listen every day for a year for just $30.